Method and apparatus for scheduling uplink rates adaptively to fast rate ramping in a packet communication system

ABSTRACT

A method and apparatus are provided for transmitting uplink rate assignment information for an uplink data transmission to a User Equipment (UE) by a Node B in a mobile communication system. The uplink rate assignment information to be transmitted for each UE is determined. The uplink rate assignment information is transmitted to the UE. The uplink rate assignment information is attached with a UE ID-specific Cyclic Redundancy Check (CRC) of the UE when directly indicating an uplink rate grant for the UE.

PRIORITY

This application is a Continuation application of U.S. Pat. No.7,899,009 issued on Mar. 1, 2011, which claims priority under 35 U.S.C.§119 to an application entitled “Method and Apparatus for SchedulingUplink Rates Adaptively to Fast Rate Ramping in a Packet CommunicationSystem” filed in the Korean Intellectual Property Office on Oct. 2, 2003and assigned Serial No. 2003-68954, the contents of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to asynchronous WCDMA (WidebandCode Division Multiple Access) communications, and in particular, to amethod and an apparatus for efficiently controlling uplink (UL) trafficrates, performing UL rate scheduling accompanied by fast rate ramping,and transmitting rate assignment information.

2. Description of the Related Art

UMTS (Universal Mobile Telecommunication Service), one of the 3^(rd)generation mobile communication systems implements WCDMA, based on theEuropean mobile communication system, GSM (Global System for Mobilecommunication). The UMTS system provides a uniform service thattransmits packetized text, digital voice and video, and multimedia dataat or above 2 Mbps to mobile subscribers or computer users around theworld. With the introduction of the concept of virtual access, UMTSallows access to any end point in a network all the time. The virtualaccess refers to packet-switched access using a packet protocol like IP(Internet Protocol).

FIG. 1 illustrates the configuration of a UTRAN (UMTS Terrestrial RadioAccess Network).

Referring to FIG. 1, a UTRAN 12 comprises RNCs (Radio NetworkControllers) 16 a and 16 b and a plurality of Node Bs 18 a, 18 b, 18 cand 18 d. The UTRAN 12 connects a UE 20 to a core network (CN) 10. Aplurality of cells may underlie the Node Bs 18 a to 18 d. The RNC 16 acontrols the Node Bs 18 a and 18 b, and the RNC 16 b controls the NodeBs 18 c and 18 d. The Node Bs 18 a to 18 d in turn control theirunderlying cells. An RNC, and Node Bs and cells under the control of theRNC are collectively called an RNS (Radio Network Subsystem).

The RNCs 16 a and 16 b assign or manage the radio resources of the NodeBs 18 a to 18 d within their coverage areas. The Node Bs 18 a to 18 dprovide radio resources. Radio resources are configured on a cell basis,and the radio resources provided by the Node Bs 18 a to 18 d are thoseof their managed cells. The UE 20 establishes a radio channel usingradio resources provided by a particular cell under a particular Node Band communicates on the radio channel. From the UE's perspective,discrimination between a Node B and a cell is meaningless. The UE 20only recognizes physical channels established on a cell basis.Therefore, the terms Node B and cell are interchangeably used herein.

A Uu interface is defined between a UE and an RNC. The hierarchicalprotocol architecture of the Uu interface is illustrated in detail inFIG. 2. The Uu interface is divided into a control plane (C-plane) forexchanging control signals between the UE and the RNC and a user plane(U-plane) for transmitting actual data.

Referring to FIG. 2, C-plane signaling 30 is processed through an RRC(Radio Resource Control) layer 34, an RLC (Radio Link Control) layer 40,a MAC (Medium Access Control) layer 42, and a PHY (PHYsical) layer 44.U-plane information 32 is processed through a PDCP (Packet Data ControlProtocol) layer 36, a BMC (Broadcast/Multicast Control) layer 38, theRLC layer 40, the MAC layer 42, and the PHY layer 44. The PHY layer 44is defined in each cell, and the MAC layer 42 through the RRC layer 34are defined in each RNC.

The PHY layer 44 provides an information delivery service using radiotransfer technology. The information delivery service corresponds tolayer 1 (L1) in an OSI (Open Systems Interconnection) model. The PHYlayer 44 is connected to the MAC layer 42 via transport channels. Themapping relationship between the transport channels and physicalchannels is determined according to how data is processed in the PHYlayer 44.

The MAC layer 42 and the RLC layer 40 of layer 2 (L2) are connected vialogical channels. The MAC layer 42 delivers data received from the RLClayer 40 on logical channels to the PHY layer 44 on appropriatetransport channels. It also delivers data received from the PHY layer 44on transport channels to the RLC layer 40 on appropriate logicalchannels. The MAC layer 42 inserts additional information into the datareceived on logical channels or transport channels or performs anappropriate operation by interpreting inserted additional information,and controls the random access. While separately not shown, aU-plane-related part of the MAC layer 42 is referred to as a MAC_d andits C-plane-related part is referred to as a MAC-c.

The RLC layer 40 controls the establishment and release of the logicalchannels. The RLC layer 40 operates in one of an acknowledged mode (AM),an unacknowledged mode (UM), and a transparent mode (TM). Typically, theRLC layer 40 segments or concatenates SDUs (Service Data Units) receivedfrom an upper layer to an appropriate size and corrects errors.

The PDCP layer 36 is an upper layer of the RLC layer 40 on the U-plane.The PDCP layer 36 is responsible for compression and decompression ofthe header of the data in the form of an IP packet, and also controlsthe lossless data delivery when a change in an RNC providing service toa particular UE occurs due to the UE's mobility.

The characteristics of the transport channels that connect the PHY layer44 to the upper layers depend on TF (Transport Format) that defines PHYlayer processing involving convolutional channel encoding, interleaving,and service-specific rate matching.

The UMTS system uses an E-DCH or EUDCH (Enhanced Uplink DedicatedChannel) to more efficiently transmit packet data from UEs on the UL. Tosupport high-speed data transmission more stably than a DCH (DedicatedChannel) used for general data transmission, the E-DCH adopts AMC(Adaptive Modulation and Coding), HARQ (Hybrid Automatic Retransmissionrequest), and Node B controlled scheduling.

FIG. 3 conceptually illustrates data transmission on the E-DCH via radiolinks. Referring to FIG. 3, reference numeral 100 denotes a Node Bsupporting the E-DCH and reference numerals 101 to 104 denote UEs thattransmit over the E-DCH. The Node B 100 detects the channel statuses ofthe UEs 101 to 104 using the E-DCH and schedules their UL datatransmissions based on the channel statuses. The scheduling is performedsuch that a noise rise measurement does not exceed a target noise risein the Node B, in order to increase the total system performance. Hence,the Node B 100 assigns a low data rate to the remote UE 104 and a highdata rate to the nearby UE 101.

FIG. 4 is a diagram illustrating a signal flow for E-DCH transmissionand reception. Referring to FIG. 4, a Node B and a UE establish an E-DCHin step 202. Step 202 involves the transmission of messages on dedicatedtransport channels. Then, the UE transmits scheduling information to theNode B in step 204. The scheduling information may contain UL channelinformation, that is, the transmit power and power margin of the UE, andthe amount of buffered data to transmit to the Node B.

In step 206, the Node B monitors the scheduling information. Whendetermining to allow the UE to transmit UL packets, the Node B transmitsScheduling Assignment information to the UE in step 208. The SchedulingAssignment information contains rate assignment information including anallowed data rate and timing.

The UE determines in step 210 the TF of the E-DCH based on theScheduling Assignment information. In steps 212 and 214, the UE notifiesat the same time the Node B of the TF and transmits UL packet data onthe E-DCH. In step 216, the Node B determines if the TF information andthe packet data have errors. In the presence of errors, the Node Btransmits an NACK (Non-Acknowledgement) signal to the UE in step 218. Inthe absence of errors, the Node B transmits an ACK (Acknowledgement)signal to the UE in step 218. In the latter case, the packet datatransmission is completed and thus the UE transmits new packet data tothe Node B on the E-DCH. In the former case, the UE retransmits the samepacket data to the Node B on the E-DCH.

Many scheduling methods are available for the above-described UL packettransmission. With reference to FIG. 5, one of the UL schedulingmethods, rate scheduling will be described.

FIG. 5 illustrates the transmission of UL/DL (Uplink/Downlink) controlinformation for rate scheduling, and UL rates controlled through therate scheduling.

Referring to FIG. 5, a UE 304 transmits a Rate Request 308 and an E-DCHpacket 310 to a Node B 302. The Node B 302 then generates and transmitsa Rate Grant 306 indicating an allowed rate to the UE 304 after ULscheduling. Both the UE 304 and the Node B 302 are provided with apreset rate table. The rate table lists a plurality of available ratescorresponding to their levels.

The UE 304 checks the amount of buffered UL data and an available powermargin, and sends a rate up or rate down request for the E-DCH to theNode B 302 by the Rate Request 308. The Node B 302 determines whether toincrease, decrease, or maintain the rate of the UE 304, taking intoaccount rate requests from other UEs under the control of the Node B 302as well as the rate request from the UE 304, and notifies the UE 304 ofthe determination result by the Rate Grant information 306.

More specifically, the UE 304 requests a rate up in an interval 312 by aRate Request 314. Upon receipt of the Rate Request 314, the Node B 302commands the UE 304 to increase its rate by a Rate Grant 318 in aninterval 316, after scheduling. Thus, in an interval 322, the UE 304transmits a UL packet at rate 11 one level higher than rate 10 used inan interval 320.

The above rate scheduling allows only a one-level rate change at a time.If the UE transmits data at a very low rate and wants to increase therate by a plurality of levels, the Node B must transmit as manyscheduling commands, for the rate increase. In this sense, theconventional rate scheduling is inflexible in rate change and causes along time delay in achieving a desired rate by the UE.

SUMMARY OF THE INVENTION

An object of the present invention is to substantially solve at leastthe above problems and/or disadvantages and to provide at least theadvantages below. Accordingly, an object of the present invention is toprovide a UL scheduling method and apparatus for transmitting UL packetson the E-DCH in an asynchronous WCDMA communication system.

Another object of the present invention is to provide a method andapparatus for reducing a time delay in the rate scheduling of UL packetsin an asynchronous WCDMA communication system.

A further object of the present invention is to provide a method andapparatus for scheduling UL packet transmissions to achieve fast rateramping in an asynchronous WCDMA communication system.

The above objects are achieved by providing a method and apparatus forefficiently controlling uplink traffic rates, performing schedulingaccompanied by fast rate ramping, and transmitting uplink rateassignment information in an asynchronous WCDMA communication system.

According to one aspect of the present invention, a method is providedfor transmitting uplink rate assignment information for an uplink datatransmission to a UE by a Node B in a mobile communication system. Theuplink rate assignment information to be transmitted for each UE isdetermined. The uplink rate assignment information is transmitted to theUE. The uplink rate assignment information is attached with a UEID-specific Cyclic Redundancy Check (CRC) of the UE when directlyindicating an uplink rate grant for the UE.

According to another aspect of the present invention, a Node B isprovided for transmitting uplink rate assignment information for anuplink data transmission to a UE in a mobile communication system. TheNode B includes a controller for determining the uplink rate assignmentinformation to be transmitted for each UE. The uplink rate assignmentinformation being attached with a UE ID-specific CRC of the UE whendirectly indicating an uplink rate grant for the UE. The Node B alsoincludes a transmitter for transmitting the uplink rate assignmentinformation to the UE.

According to a further aspect of the present invention, a method isprovided for transmitting uplink data to a Node B by a UE in a mobilecommunication system. Uplink rate assignment information for an uplinkdata transmission is received from the Node B. The uplink rateassignment information is attached with a UE ID-specific CyclicRedundancy Check (CRC) of the UE when directly indicating an uplink rategrant for the UE. The uplink data is transmitted to a Node B based onthe uplink rate assignment information.

According to still another aspect of the present invention, a UE isprovided for transmitting uplink data to a Node B in a mobilecommunication system. The UE includes a receiver for receiving uplinkrate assignment information for uplink data transmission from the NodeB. The uplink rate assignment information is attached with a UEID-specific Cyclic Redundancy Check (CRC) of the UE when directlyindicating an uplink rate grant for the UE. The UE also includes atransmitter for transmitting the uplink data to the Node B. The UEfurther includes a controller for controlling transmission of the uplinkdata to the Node B based on the uplink rate assignment information.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 illustrates the configuration of a UTRAN;

FIG. 2 illustrates the hierarchical protocol architecture of theinterface between a UE and an RNC;

FIG. 3 conceptually illustrates a typical data transmission on the E-DCHvia radio links;

FIG. 4 is a diagram illustrating a signal flow for E-DCH transmissionand reception;

FIG. 5 illustrates transmission of UL/DL control information for ratescheduling, and UL rates controlled through the rate scheduling;

FIG. 6 illustrates transmission of rate assignment information which isdetermined through UL scheduling according to an embodiment of thepresent invention;

FIG. 7 is a flowchart illustrating an operation for transmitting therate assignment information in a Node B according to the embodiment ofthe present invention;

FIG. 8 is a block diagram of an apparatus for transmitting the rateassignment information determined by UL scheduling in the Node Baccording to the embodiment of the present invention;

FIG. 9 is a flowchart illustrating an operation for receiving the rateassignment information determined by UL scheduling in a UE according tothe embodiment of the present invention;

FIG. 10 is a block diagram of an apparatus for receiving the rateassignment information determined by UL scheduling in the UE accordingto the embodiment of the present invention;

FIG. 11 is a conceptual view illustrating transmission of rateassignment information determined by UL scheduling according to anotherembodiment of the present invention;

FIG. 12 is a conceptual view illustrating transmission of rateassignment information determined by UL scheduling according to afurther embodiment of the present invention;

FIG. 13 is a conceptual view illustrating transmission of rateassignment information determined by UL scheduling according to yetanother embodiment of the present invention;

FIG. 14 is a flowchart illustrating an operation for transmitting therate assignment information in the Node B according to the embodiment ofthe present invention; and

FIG. 15 is a flowchart illustrating an operation for receiving the rateassignment information in the UE according to the embodiment of thepresent invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

Preferred embodiments of the present invention will be described hereinbelow with reference to the accompanying drawings. In the followingdescription, well-known functions or constructions are not described indetail since they would obscure the invention in unnecessary detail.

FIG. 6 illustrates transmission of rate assignment information which isdetermined through UL scheduling according to an embodiment of thepresent invention.

Referring to FIG. 6, a UE 408 transmits a UL packet 412 on the E-DCH toa Node B 402 which controls the scheduling of the UL packet transmissionof the UE 408. DL control information used for scheduling is a RateIndication 404 and a Rate Up/Down 406. UL control information forscheduling is a UE Status Report 410 that indicates the schedulinginformation of the UE 408.

To transmit an E-DCH packet, the UE 408 first transmits the UE StatusReport 410 to the Node B 402. At the same time, the UE can transmit theE-DCH packet at a rate lower than a threshold (i.e. rate 1) withoutexchanging any information with the Node B 402.

The Node B 402 collects UE Status Reports from multiple UEs, determinesrates for the individual UEs through scheduling, and transmits rateassignment information to the UE 408 and other USs (not shown). The rateassignment information is the Rate Indication 404 and the Rate Up/Down406. If the rate of the UE 408 is to be changed by two or more levels,the Node B 402 directly instructs the UE 408 an assigned rate by theRate Indication 404. On the other hand, if the rate is to be changed byone level or it is to be maintained, the Node B 402 commands the UE 408to increase/decrease its rate by one level or maintain it by the RateUp/Down 406.

The UE 408 transmits the UE Status Report 410 either periodically orupon the generation of new data in its buffer. Transmission upongeneration of an event, such as the transmission of the UE Status Report410 upon the generation of new data in the buffer, is referred to asevent-triggered transmission.

More specifically, when the UE 408 transmits a UE Status Report 416 tothe Node B 402 in an interval 414, the Node B 402 determines a rate forthe UE 408 in an interval 418. If the determined rate is rate 10 and istwo or more levels greater than the current rate of the UE 408, the NodeB 402 instructs the UE 408 that the assigned rate is rate 10 by a RateIndication 420. In an interval 422, the UE 408 transmits an E-DCH packetat rate 10 according to the Rate Indication 420.

In the next interval 424, the Node B 402 again determines a rate for theUE 408. If rate 10 is assigned, the Node B 402 tells the UE 408 that nochange is made in the rate by a Rate Up/Down 426. Upon receipt of theRate Up/Down 426, the UE transmits the E-DCH packet data at rate 10 inan interval 428. Thereafter, the UE 408 transmits the E-DCH packet data,while controlling its rate level by level or maintains the rateaccording to the Rate Up/Down 406.

When new data enters the buffer in an interval 430, the UE 408 transitsthe UE Status Report 410 to the Node B 402. In an interval 432, the NodeB 402 needs to assign a much higher rate, e.g., rate 14, and thustransmits to the UE 408 the Rate Indication 406 indicating rate 14.Hence, the UE 408 transmits the E-DCH packet data at rate 14 two or morelevels higher than rate 11 in an interval 436.

Hereinbelow, a description will be made of a procedure and apparatus fortransmitting/receiving rate assignment information in a rate schedulingaccompanied by fast rate ramping.

FIG. 7 is a flowchart illustrating an operation for transmitting therate assignment information in a Node B according to the embodiment ofthe present invention. The Node B determines whether to transmit a RateIndication or a Rate up/Down and assigns a rate to the UE by thedetermined rate assignment information.

Referring to FIG. 7, the Node B detects in step 502 the rate of theE-DCH used in the previous interval and determines in step 504 a rate toassign to the UE by scheduling. In step 506, the Node B compares theprevious rate with the determined current rate. If the differencebetween the two rates is two or more levels, the Node B maps the currentrate to a Rate Indication referring to a pre-stored rate table andtransmits to the UE in step 520 the Rate Indication.

If the difference between the two rates is zero or one level, the Node Bcompares the two rates again to transmit a Rate Up/Down to the UE instep 508. If the current rate is higher than the previous rate, the NodeB goes to step 510. If the current rate is lower than the previous rate,the Node B goes to step 514. If the current rate is equal to theprevious rate, the Node B goes to step 512.

In step 510, 512 or 514, the Node B maps the current rate to a RateUp/Down. More specifically, the Node B maps the rate to rate up, forexample, “+1” in step 510, to rate maintenance, for example, “0” in step512, and to rate down, for example, “−1” in step 514. The Node Btransmits the Rate Up/Down to the UE in step 516.

FIG. 8 is a block diagram of an apparatus for transmitting the rateassignment information determined by UL scheduling in the Node Baccording to the embodiment of the present invention.

Referring to FIG. 8, a transmission controller 622 determines whether totransmit a Rate Indication or a Rate Up/Down for every transmissioninterval in the procedure illustrated in FIG. 7 and provides thedetermination result to a Rate Indication generator 602 and a RateUp/Down generator 614. The Rate Indication generator 602 generates aRate Indication for the UE in intervals 418 and 432 of FIG. 6. Amultiplexer (MUX) 606 multiplexes the Rate Indication with the ID(Identifier) of the UE read from a UE ID memory 604. The multiplexedinformation is attached with a CRC in a CRC adder 608 and tail bits areadded in a tail bits adder 610, and encoded in a convolutional encoder612. Meanwhile, in intervals other than the intervals to transmit theRate Indication, the Rate Up/Down generator 614 generates a RateUp/Down. A repetition encoder 616 encodes the Rate Up/Down. A MUX 618multiplexes the outputs of the convolutional encoder 612 and therepetition encoder 616. A modulator 620 modulates the output of the MUX618 to a radio signal and transmits it in the air.

FIG. 9 is a flowchart illustrating an operation for receiving the rateassignment information determined by UL scheduling in the UE accordingto the embodiment of the present invention.

Referring to FIG. 9, the UE receives the Rate Indication from the Node Bon a rate indication channel in step 702. In step 704, the UE acquires aUE ID from the Rate Indication and compares it with its ID to determineif the Rate Indication is destined for the UE. If they are identical,the UE sets a rate corresponding to the Rate Indication in a pre-storedrate table as the rate for the E-DCH in the current interval in step 718and transmits in step 716 the E-DCH packet data at the rate.

On the contrary, if the UE IDs are different, the UE receives the RateUp/Down on the rate indication channel in step 706. Also, in the absenceof the Rate Indication in the rate indication channel, the UE receivesthe Rate Up/Down. In step 708, the UE interprets the Rate Up/Down. Ifthe Rate Up/Down indicates rate up, the UE increases its rate by onelevel in step 710. If the Rate Up/Down indicates rate maintenance, theUE maintains its rate in step 712. If the Rate Up/Down indicates ratedown, the UE decreases its rate by one level in step 714. In step 716,the UE transmits the E-DCH packet data at the controlled rate.

FIG. 10 is a block diagram of an apparatus for receiving the rateassignment information determined by UL scheduling in the UE accordingto the embodiment of the present invention.

Referring to FIG. 10, a signal received on the rate indication channelis demodulated in a demodulator 802 and demultiplexed into a signalincluding the Rate Indication or a signal including the Rate Up/Down ina demultiplexer (DEMUX) 804.

A Viterbi decoder 806 decodes the Rate Indication-including signal. ACRC checker 808 detects a CRC from the decoded data. If the decoded datahas no errors in a CRC check, the CRC checker 808 outputs the dataexcept for the CRC to a DEMUX 810. The DEMUX 810 demultiplexes theoutput of the CRC checker 808 into the Rate Indication and a UE ID andprovides them to a Rate Indication analyzer 812 and a UE ID memory 814,respectively. A reception controller 820 compares the extracted UE IDwith the ID of the UE in every interval, determines whether the RateIndication or the Rate Up/Down is to be received in the procedureillustrated in FIG. 9, and outputs the determination result to the RateIndication analyzer 812 and a Rate Up/Down analyzer 818.

It can be further contemplated as another embodiment of the presentinvention that the CRC extracted in the CRC checker 808 is used as a UEID. In this case, because a UE can be identified by a CRC, the CRCchecker 808 outputs the Rate Indication directly without using the DEMUX810.

If the extracted UE ID is identical to the ID of the UE, the RateIndication analyzer 812 determines the current rate by analyzing theRate Indication. If they are different, the Rate Up/Down-includingsignal is provided to a repetition decoder 816. The repetition decoder816 decodes the received signal and outputs the Rate Up/Down to the RateUp/Down analyzer 818. The Rate Up/Down analyzer 818 determines thecurrent rate by controlling the previous rate according to the RateDown/Up.

In accordance with the embodiment of the present invention, the UE firstchecks a UE ID in every interval to receive the Rate Indication. If theUE ID is identical to the ID of the UE, the UE reads the RateIndication. If they are different, the UE reads the Rate Up/Downinstead. Considering that the Rate Indication is transmitted only when agreat change occurs to the rate of the UE, it is less frequent than theRate Up/Down. Especially when a plurality of UEs transmit UL packets toone Node B, fast rate ramping that requires the transmission of the RateIndication does not occur often in most cases. In this context, thechecking of the UE ID to determine the presence or absence of the RateIndication for the UE may become a constraint to the UE.

Therefore, the present invention can be implemented in other embodimentssuch that scheduling is performed more flexibly, while minimizing theconstraint of acquiring of the Rate Indication by the UEs. This can beachieved by adaptively changing the transmission/reception timing of therate assignment information according to situations.

In accordance with another embodiment of the present invention, thetransmission of the Rate indication is limited to predetermined timeintervals in order to relieve the UE of the constraint of receiving theRate Indication. The UE checks a received UE ID during the predeterminedintervals. If the read UE ID is identical to the ID of the UE, the UEreads the Rate Indication. If they are different, the UE reads the RateUp/Down. In other intervals, the UE just checks the Rate Up/Down withoutthe need for checking a received UE ID.

FIG. 11 is a conceptual view illustrating transmission of rateassignment information determined by UL scheduling according to thesecond embodiment of the present invention.

Referring to FIG. 11, a Node B 902 assigns a UL rate for the E-DCH to aUE 908 through scheduling. To notify the UE 908 of the assigned UL rate,the Node B 902 uses a Rate Indication 904 or a Rate Up/Down 906. The UE908 transmits periodically or in an event-triggered manner a UE StatusReport 910 for use in scheduling to the Node B 902. It also transmitsE-DCH packet data 912 at the assigned rate to the Node B 902. In thesecond embodiment of the present invention, the Node B 902 transmits theRate Indication 904 to the UE 908 only in an interval 916 in which itreceives the first UE Status Report 910 from the UE 908. Then, the NodeB transmits the Rate Indication 904 every predetermined period of timeindicated by reference numerals 922 and 924, for example, in intervals918 and 920, while it transmits a Rate Up/Down 906 in the otherintervals, for example, in a period 926.

If the Node B 902 determines that a rate can be assigned by the RateUp/Down 906 in the intervals 916, 918 and 920, that is, if a rate changeis only one level or no rate change is made, it transmits the RateUp/Down 906 instead of the Rate Indication 904. The period oftransmitting the Rate Indication 904 is fixed by the system or set by acontrol signal from a higher layer during a setup for UL packettransmission.

The operations of the Node B and the UE according to the secondembodiment of the present invention will be described.

FIG. 14 is a flowchart illustrating an operation for transmitting ULrate assignment information in the Node B according to the secondembodiment of the present invention.

Referring to FIG. 14, the Node B determines to transmit the RateIndication in the current interval by checking if the current intervalis an interval predetermined for transmission of the Rate Indication instep 1202. In the second embodiment of the present invention, the RateIndication is supposed to be transmitted every predetermined period oftime after the start of communications.

If the Rate Indication is not scheduled to be transmitted in the currentinterval, the Node B determines a rate for the UE in the currentinterval in step 1204. The Node B sets the current rate for the UE sothat it is different from the previous rate by one level or no change ismade to the rate. In step 1206, the Node B compares the current ratewith the previous rate. If the current rate is higher than the previousrate by one level, the Node B maps the Rate Up/Down to +1 in step 1208.If the current rate is equal to the previous rate, the Node B maps theRate Up/Down to 0 in step 1210. If the current rate is lower than theprevious rate by one level, the Node B maps the Rate Up/Down to −1 instep 1212. The Node B transmits the Rate Up/Down to the UE in step 1214.

If transmission of the Rate Indication is available in the currentinterval in step 1202, the Node B checks the previous rate in step 1216and determines the current rate for the UE in step 1218. If thedifference between the two rates is two or more levels in step 1220, theNode B goes to step 1222, otherwise, the process goes to step 1206. TheNode B operates in the above-described manner in step 1206. Meanwhile,in step 1222, the Node B maps the current rate to the Rate Indication.Then the Node B transmits the Rate Indication to the UE in step 1224.

FIG. 15 is a flowchart illustrating an operation for receiving the rateassignment information in the UE according to the second embodiment ofthe present invention.

Referring to FIG. 15, the UE determines if reception of the RateIndication is available in the current interval by checking if thecurrent interval is a predetermined interval for the reception of theRate Indication in step 1302. The Rate Indication can be received everypredetermined period of time after the start of communications. If theRate Indication is not scheduled to be received in the current interval,the UE receives the Rate Up/Down in step 1304.

In step 1306, the UE analyzes the Rate Up/Down. If the Rate Up/Down is+1, indicating rate up, the UE determines that the current rate ishigher than the previous rate by one level in step 1308. If the RateUp/Down is 0, the UE determines that the current rate is equal to theprevious rate in step 1310. If the Rate Up/Down is −1, the UE determinesthat the current rate is lower than the previous rate by one level instep 1312. In step 1314, the UE checks the previous rate. In step 1316,the UE sets the current rate according to the determination result ofstep 1308, 1310 or 1312 and the previous rate.

If reception of the Rate Indication is available in step 1302, the UEreceives the Rate Indication in step 1318 and compares a UE ID receivedalong with the Rate Indication with the ID of the UE in step 1320. Ifthey are different, the UE determines the current rate according to theprevious rate in the above-described manner in step 1304. If the UE IDsare identical, the UE reads the Rate Indication in step 1322 anddetermines the current rate based on the Rate Indication in step 1316.

In a third embodiment of the present invention, the Node B transmits theRate Indication to the UE only if it receives the UE Status Report fromthe UE, in order to relieve the UE of the constraint of receiving theRate Indication. Therefore, only when it transmits the UE Status Reportto the Node B, the UE attempts to read the Rate Indication. During othertimes, the UE reads only the Rate Up/Down, knowing that there is no RateIndication to receive.

FIG. 12 is a conceptual view illustrating transmission of rateassignment information determined by UL scheduling according to thethird embodiment of the present invention.

Referring to FIG. 12, a Node B 1002 assigns a UL rate for the E-DCH to aUE 1008 through scheduling. To notify the UE 1008 of the assigned ULrate, the Node B 1002 uses a Rate Indication 1004 or a Rate Up/Down1006. The UE 1008 transmits periodically or in an event-triggered mannera UE Status Report 1010 for use in scheduling to the Node B 1002. Italso transmits E-DCH packet data 1012 at the assigned rate to the Node B1002.

In the third embodiment of the present invention, the Node B 1002transmits the Rate Indication 1004 to the UE 1008 in intervals 1016,1020 and 1024 in which it receives a UE Status Report 1010 transmittedin intervals 1014, 1018 and 1022 by the UE 1008. During other intervals,the Node B 1002 transmits a Rate Up/Down 1006. However, if a rate can beassigned to the UE 1008 by the Rate Up/Down 1006 in the intervals 1016,1020 and 1024, that is, if a rate change is only one level or no ratechange is made, the Node B transmits the Rate Up/Down 1006 instead ofthe Rate Indication 1004.

The operations of the Node B and the UE according to the thirdembodiment of the present invention will be described with reference toFIGS. 14 and 15.

FIG. 14 is a flowchart illustrating an operation for transmitting ULrate assignment information in the Node B according to the thirdembodiment of the present invention.

Referring to FIG. 14, the Node B determines to transmit the RateIndication in the current interval by checking if the UE Status Reporthas been received in step 1202. In the third embodiment of the presentinvention, if the UE Status Report has been received within apredetermined period of time, the Node B determines that the RateIndication can be transmitted in the current interval.

If the Rate Indication is not supposed to be transmitted in the currentinterval, the Node B determines a rate for the UE in the currentinterval in step 1204. The Node B sets the current rate for the UE sothat it is different from the previous rate by one level or no change ismade to the rate. In step 1206, the Node B compares the current ratewith the previous rate. If the current rate is higher than the previousrate by one level, the Node B maps the Rate Up/Down to +1 in step 1208.If the current rate is equal to the previous rate, the Node B maps theRate Up/Down to 0 in step 1210. If the current rate is lower than theprevious rate by one level, the Node B maps the Rate Up/Down to −1 instep 1212. The Node B transmits the Rate Up/Down to the UE in step 1214.

On the other hand, if transmission of the Rate Indication is availablein the current interval in step 1202, the Node B checks the previousrate in step 1216 and determines the current rate for the UE in step1218. If the difference between the two rates is two or more levels instep 1220, the Node B goes to step 1222, otherwise, it goes to step1206. The Node B operates in the afore-described manner in step 1206.Meanwhile, in step 1222, the Node B maps the current rate to the RateIndication. Then the Node B transmits the Rate Indication to the UE instep 1224.

FIG. 15 is a flowchart illustrating an operation for receiving the rateassignment information in the UE according to the third embodiment ofthe present invention.

Referring to FIG. 15, the UE determines reception of the Rate Indicationis available in the current interval by checking if it has transmittedthe UE Status Report in step 1302. If it has transmitted the UE StatusReport within a predetermined period of time, the UE determines that itcan receive the Rate Indication in the current interval. If the RateIndication is not scheduled to be received in the current interval, theUE receives the Rate Up/Down in step 1304.

In step 1306, the UE analyzes the Rate Up/Down. If the Rate Up/Down is+1, indicating rate up, the UE determines that the current rate isgreater than the previous rate by one level in step 1308. If the RateUp/Down is 0, the UE determines that the current rate is equal to theprevious rate in step 1310. If the Rate Up/Down is −1, the UE determinesthat the current rate is less than the previous rate by one level instep 1312. In step 1314, the UE checks the previous rate. In step 1316,the UE sets the current rate according to the determination result ofstep 1308, 1310 or 1312 and the previous rate.

If reception of the Rate Indication is available in step 1302, the UEreceives the Rate Indication in step 1318 and compares a UE ID receivedalong with the Rate Indication with the ID of the UE in step 1320. Ifthey are different, the UE determines the current rate according to theprevious rate in the afore-described manner in step 1304. If the UE IDsare identical, the UE determines the current rate based on the RateIndication in step 1322.

In a fourth embodiment of the present invention, the Node B transmitsthe Rate Indication to the UE every predetermined period of time or ifit receives the UE Status Report from the UE, in order to relieve the UEof the constraint of receiving the Rate Indication. That is, the Node Bcan transmit the Rate Indication when receiving the UE Status Reportfrom the UE or in predetermined intervals. Therefore, the UE attempts toread the Rate Indication in corresponding intervals. In the other times,the UE reads only the Rate Up/Down, knowing that there is no RateIndication to receive either where it has not transmitted the UE StatusReport and or where the predetermined period of time has not elapsed.

FIG. 13 is a conceptual view illustrating transmission of rateassignment information determined by UL scheduling according to thefourth embodiment of the present invention.

Referring to FIG. 13, a Node B 1102 assigns a UL rate for the E-DCH to aUE 1108 through scheduling. To notify the UE 1108 of the assigned ULrate, the Node B 1102 uses a Rate Indication 1104 or a Rate Up/Down1106. The UE 1108 transmits periodically or in an event-triggered mannera UE Status Report 1110 for use in scheduling to the Node B 1102. Italso transmits E-DCH packet data 1112 at the assigned rate to the Node B1102.

In the fourth embodiment of the present invention, the Node B 1102transmits the Rate Indication 1104 to the UE 1108 when receiving the UEStatus Report 1110 or every predetermined period of time. That is, theUE 1108 transmits the first UE Status Report 1110 to the Node B 1102 inan interval 1114 to start UL packet transmission. The Node B 1102 thentransmits the Rate Indication 1104 in response to the UE Statue Report1110 in an interval 1116 to the UE 1108. Since then, the Node B 1102repeatedly transmits the Rate Indication 1104 every predetermined periodof time 1126 after the interval 1116. That is, the Node B 1102 cantransmit the Rate Indication in intervals 1118 and 1124.

After starting packet transmission, the UE 1108 transmits the UE StatusReport 1110 to the Node B 1102 in an interval 1120. The Node B 1102transmits to the UE 1108 the Rate Indication 1104 in an interval 1122 inwhich it receives the UE Status Report 1110. That is, the Node B 1102can transmit the Rate Indication 1104 to the UE 1108 when it receivesthe UE Status Report 1110 or every predetermined time of period 1126. Inthe other times, the Node B 1102 transmits the Rate Up/Down 1106 to theUE 1108.

However, if a rate can be assigned to the UE 1108 by the Rate Up/Down1106 in the intervals 1116, 1118, 1122 and 1124, that is, if a ratechange is only one level or no rate change is made, the Node B transmitsthe Rate Up/Down 1106 instead of the Rate Indication 1104. The period oftransmitting the Rate Indication 1104 is fixed by the system or set by acontrol signal from a higher layer during a setup for UL packettransmission.

The operations of the Node B and the UE according to the fourthembodiment of the present invention will be described with reference toFIGS. 14 and 15.

FIG. 14 is a flowchart illustrating an operation for transmitting ULrate assignment information in the Node B according to the fourthembodiment of the present invention.

Referring to FIG. 14, the Node B determines to transmit the RateIndication in the current interval by checking if the UE Status Reporthas been received or a predetermined time of period has elapsed in step1202. In the fourth embodiment of the present invention, if it is timeto transmit the Rate Indication according to the predetermined time ofperiod, or the UE Status Report has been received, the Node B determinesthat the Rate Indication can be transmitted in the current interval. TheRate Indication is scheduled to be transmitted periodically thepredetermined period of time after the start of communications, or whenthe UE Status Report is received within a predetermined previousinterval.

If the Rate Indication is not scheduled to be transmitted in the currentinterval, the Node B determines a rate for the UE in the currentinterval in step 1204. The Node B sets the current rate for the UE sothat it is different from the previous rate by one level or no change ismade to the rate. In step 1206, the Node B compares the current ratewith the previous rate. If the current rate is greater than the previousrate by one level, the Node B maps the Rate Up/Down to +1 in step 1208.If the current rate is equal to the previous rate, the Node B maps theRate Up/Down to 0 in step 1210. If the current rate is less than theprevious rate by one level, the Node B maps the Rate Up/Down to −1 instep 1212. The Node B transmits the Rate Up/Down to the UE in step 1214.

If transmission of the Rate Indication is available in the currentinterval in step 1202, the Node B checks the previous rate in step 1216and determines the current rate for the UE in step 1218. If thedifference between the two rates is two or more levels in step 1220, theNode B goes to step 1222. Otherwise, it goes to step 1206. The Node Boperates in the afore-described manner in step 1206. Meanwhile, in step1222, the Node B maps the current rate to the Rate Indication. Then theNode B transmits the Rate Indication to the UE in step 1224.

FIG. 15 is a flowchart illustrating an operation for receiving the rateassignment information in the UE according to the fourth embodiment ofthe present invention.

Referring to FIG. 15, the UE determines if reception of the RateIndication is available in the current interval by checking if it hastransmitted the UE Status Report or the current interval is an intervalpredetermined for reception of the Rate Indication in step 1302. TheRate Indication can be received every predetermined period of time afterthe start of communications. Also, if it has transmitted the UE StatusReport within a predetermined period of time, the UE considers that itcan receive the Rate Indication in the current interval. If the RateIndication is not supposed to be received in the current interval, theUE receives the Rate Up/Down in step 1304.

In step 1306, the UE analyzes the Rate Up/Down. If the Rate Up/Down is+1, indicating rate up, the UE determines that the current rate isgreater than the previous rate by one level in step 1308. If the RateUp/Down is 0, the UE determines that the current rate is equal to theprevious rate in step 1310. If the Rate Up/Down is −1, the UE determinesthat the current rate is less than the previous rate by one level instep 1312. In step 1314, the UE checks the previous rate. In step 1316,the UE sets the current rate according to the determination result ofstep 1308, 1310 or 1312 and the previous rate.

If reception of the Rate Indication is available in step 1302, the UEreceives the Rate Indication in step 1318 and compares a UE ID receivedalong with the Rate Indication with the ID of the UE in step 1320. Ifthey are different, the UE determines the current rate according to theprevious rate in the afore-described manner in step 1304. On thecontrary, if the UE IDs are identical, the UE determines the currentrate based on the Rate Indication in step 1322.

The structures of the transmitting apparatus in the BS illustrated inFIG. 8 and the receiving apparatus in the UE illustrated in FIG. 10 arecommon to the second, third and fourth embodiments of the presentinvention, except that the transmission controller 622 in thetransmitting apparatus determines to transmit the Rate Indication usingdifferent criteria including a predetermined transmission time ofperiod, presence or absence of the UE Status Report, and the differencebetween the previous and current rates according to the second, thirdand fourth embodiments of the present invention. The receptioncontroller 820 in the receiving apparatus also determines if it canreceive the Rate Indication using different criteria including UE IDmatching, a predetermined reception period of time, and transmission ornon-transmission of the UE Status Report according to the second, thirdand fourth embodiments of the present invention.

As described above, the present invention advantageously enables fastrate ramping through UL rate scheduling in an asynchronous WCDMAcommunication system using the E-DCH. Thus, scheduling becomes moreflexible and the total system performance is improved. Furthermore, a UEis relieved of the constraint of monitoring a rate indication channel toreceive a Rate Indication.

While the invention has been shown and described with reference tocertain preferred embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims.

What is claimed is:
 1. A method for transmitting uplink rate assignment information for an uplink data transmission to a User Equipment (UE) by a Node B in a mobile communication system, comprising the steps of: determining the uplink rate assignment information to be transmitted for each UE; and transmitting the uplink rate assignment information to the UE, wherein the uplink rate assignment information is attached with a UE ID-specific Cyclic Redundancy Check (CRC) of the UE when directly indicating an uplink rate grant for the UE, and the uplink rate assignment information is transmitted without the UE ID-specific CRC to the UE when indicating an uplink rate change in states or an uplink rate maintain.
 2. The method of claim 1, wherein the uplink rate assignment information is used when determining a Transport Format (TF) of an uplink channel for the uplink data transmission by the UE.
 3. The method of claim 2, wherein determination of the TF for the uplink channel comprises a determination of a maximum allowed power ratio associated with the uplink channel.
 4. The method of claim 1, wherein the uplink rate assignment information comprises a maximum allowed power ratio for the uplink data transmission.
 5. A Node B for transmitting uplink rate assignment information for an uplink data transmission to a User Equipment (UE) in a mobile communication system, comprising: a controller for determining the uplink rate assignment information to be transmitted for each UE, wherein the uplink rate assignment information is attached with a UE ID-specific Cyclic Redundancy Check (CRC) of the UE when directly indicating an uplink rate grant for the UE, and the uplink rate assignment information is transmitted without the UE ID-specific CRC to the UE when indicating an uplink rate change in states or an uplink rate maintain; and a transmitter for transmitting the uplink rate assignment information to the UE.
 6. The Node B of claim 5, wherein the uplink rate assignment information is used when determining a Transport Format (TF) of an uplink channel for the uplink data transmission by the UE.
 7. The Node B of claim 6, wherein determination of the TF for the uplink channel comprises a determination of a maximum allowed power ratio associated with the uplink channel.
 8. The Node B of claim 5, wherein the uplink rate assignment information comprises a maximum allowed power ratio for the uplink data transmission.
 9. A method for transmitting uplink data to a Node B by a User Equipment (UE) in a mobile communication system, comprising the steps of: receiving uplink rate assignment information for an uplink data transmission from the Node B, wherein the uplink rate assignment information is attached with a UE ID-specific Cyclic Redundancy Check (CRC) of the UE when directly indicating an uplink rate grant for the UE, and the uplink rate assignment information is transmitted without the UE ID-specific CRC to the UE when indicating an uplink rate change in states or an uplink rate maintain; and transmitting the uplink data to a Node B based on the uplink rate assignment information.
 10. The method of claim 9, wherein transmitting the uplink data comprises determining a Transport Format (TF) of an uplink channel for the uplink data transmission based on the uplink rate assignment information.
 11. The method of claim 10, wherein determination of the TF for the uplink channel comprises a determination of a maximum allowed power ratio associated with the uplink channel.
 12. The method of claim 9, wherein the uplink rate assignment information comprises a maximum allowed power ratio for the uplink data transmission.
 13. The method of claim 9, wherein receiving uplink rate assignment information comprises: determining whether the uplink rate assignment information, indicating the uplink rate change in states or the uplink rate maintain, is received when the uplink rate grant attaching the UE ID-specific CRC is not received.
 14. A User Equipment (UE) for transmitting uplink data to a Node B in a mobile communication system, comprising: a receiver for receiving uplink rate assignment information for uplink data transmission from the Node B, wherein the uplink rate assignment information being attached with a UE ID-specific Cyclic Redundancy Check (CRC) of the UE when directly indicating an uplink rate grant for the UE, and the uplink rate assignment information is transmitted without the UE ID-specific CRC to the UE when indicating an uplink rate change in states or an uplink rate maintain; a transmitter for transmitting the uplink data to the Node B; and a controller for controlling transmission of the uplink data to the Node B based on the uplink rate assignment information.
 15. The UE of claim 14, wherein the controller determines a Transport Format (TF) of an uplink channel for the uplink data transmission based on the uplink rate assignment information.
 16. The UE of claim 15, wherein determination of the TF for the uplink channel comprises a determination of a maximum allowed power ratio associated with the uplink channel.
 17. The UE of claim 14, wherein the uplink rate assignment information comprises a maximum allowed power ratio for uplink data transmission.
 18. The UE of claim 14 wherein the controller determines whether the uplink rate assignment information, indicating the uplink rate change in states or the uplink rate maintain, is received when the uplink rate grant attaching the UE ID-specific CRC is not received. 